I am very fortunate, as i am firends with my enginebuilder, and we sit and chat in depth about which engine i am building at the time and the goals i want. My last 426 wedge we just built was a nice piece. we picked a goal and a hp and tq rating and went from there.
Short block...
Can you achieve what you need with a factory style block? if not aftermarket.
Steel crank forged H bean or I beam rods, forged pistons.
The bottom end is the platform for the rest. After that, look at which cylinder head works with the rpm range hp range and cubic inch of the motor. Camshaft follows the same consideration. We went with a mild camshaft,small CC runner head and the result was a serious torque motor on pump gas that runs hard to 6000 rpm. Goal achieved.
Big cube motors are easier to get 600 hp 650 tq without a lot of effort and large cylinder heads. You can keep it simple and drivable with mild parts.